The present invention relates to fuel injection systems and, more specifically, to electronic fuel injection systems.
Typically, a throttle valve controls the air flow into an intake manifold in an engine. In many fuel injection (FI) systems, the air flow into the engine is determined indirectly using coordinates defined by a throttle valve angle and the speed at which the engine is operating. For these systems to function correctly, the relationship between the throttle valve angle and the actual flow area within the housing of the throttle valve must be maintained within very close tolerances. In many FI systems, the throttle valve angle is measured by a throttle position sensor (TPS). In many systems, the TPS outputs an electrical resistance value which directly relates to the sensed throttle angle.
In existing systems, the TPS needs to be manually adjusted when installed so that at a physical or measured throttle angle, the actual airflow matches the airflow expected or calculated by a control unit at that same electronically measured or derived throttle angle. In other words, the TPS has to be adjusted so that the ignition and fuel maps residing within the control unit are aligned with the hardware.
Conventionally, TPS adjustment is performed during assembly of the throttle body. First, the TPS is loosely installed on the throttle body. The throttle valve is adjusted to provide a predetermined airflow on an air-flow bench. The TPS is physically rotated to achieve the desired electrical resistance for that airflow and permanently attached to the throttle body. When this installation method is used, the throttle body and the TPS must be serviced as a unit.
A problem associated with the conventional installation method is that since dealers in the field typically do not have access to air flow benches, a complicated service procedure must be used if the control unit, TPS, or throttle body needed to be replaced. Further, many dealers are not able to perform the procedure correctly due to its complexity. An incorrectly installed TPS can greatly effect fueling calculations, especially at small throttle valves angles. Improper or incorrect fueling calculations reduce engine efficiency.
In one embodiment, the invention provides a fuel injection system that performs an automatic adjustment function for the TPS and throttle valve position. The function can be performed while the engine is intact and running. The engine runs in an idle mode and includes an exhaust manifold and a fuel injection system. The fuel injection system includes a control unit, a throttle valve, and at least one sensor providing an output. The fuel injection system is operable to perform in a closed-loop mode.
In another embodiment, the invention provides a method of calculating an offset of a throttle-position sensor in an engine. The method includes operating the engine in idle mode, operating the electronic fuel injection system in closed-loop mode, computing an expected angle of the throttle valve, and obtaining a first output from the plurality of sensors. The method also includes determining an actual angle of the throttle valve using the output from the at least one sensor, determining an offset between the expected angle of the throttle valve and the actual angle of the throttle valve and adding the offset to the actual angle of the throttle valve to generate a corrected angle of the throttle valve.
In another embodiment, the invention provides a method of performing fueling calculations for a fuel injection system in an engine. The fuel injection system is capable of operating in a plurality of functioning modes including a closed-loop mode. The fuel injection system has a control unit, a throttle valve, an exhaust manifold, and a plurality of sensors providing outputs. The engine is capable of operating at stoichiometry and capable of operating in a plurality of operating modes including an idle mode.
The method includes computing an expected angle of the throttle valve, determining a functioning mode of the fuel injection system, determining an operating mode of the engine, and obtaining a first output from a first sensor in the plurality of sensors when the fuel injection system is operating in the closed-loop mode and when the engine is operating in the idle mode. The method also includes determining an actual angle of the throttle valve using the first output from the first sensor, determining an offset between the expected angle of the throttle valve and the actual angle of the throttle valve and adding the offset to the actual angle of the throttle valve to result in a corrected angle of the throttle valve. The method further includes computing fueling calculations based on the corrected angle of the throttle valve.
In another embodiment, the invention provides a fuel injection system in an engine. The system includes a throttle body having a throttle valve and a plurality of sensors generating outputs. The plurality of sensors include a first sensor measuring a sensed throttle valve angle and providing an output corresponding to the sensed throttle valve angle. The system also includes an electronic control unit coupled to the plurality of sensors and that is operable to receive outputs generated by the plurality of sensors. The electronic control unit includes a first computational module operable to determine a theoretical throttle valve angle, a second computational module operable to determine a measured throttle valve angle based on the output corresponding to the sensed throttle valve angle and a third computational module operable to determine an offset between the theoretical throttle valve angle and the measured throttle valve angle. The control unit also includes a summing module operable to add the offset to the measured throttle valve angle to produce a corrected throttle valve angle, a fueling computational module operable to determine fueling calculations based on the corrected throttle valve angle and an analyzing module operable to analyze the outputs from the plurality of sensors.
In another embodiment, the invention provides a fuel injection system in an engine. The system includes a throttle body having a throttle valve, a first sensor, and a control unit coupled to the first sensor. The first sensor measures a sensed throttle valve angle and provides a first output corresponding to the sensed throttle valve angle. The control unit is operable to receive the output generated by the first sensor, operable to compute an expected throttle valve angle, operable to determine an offset between the expected throttle valve angle and the sensed throttle valve angle, operable to determine a corrected throttle valve angle, and operable to compute fueling calculations based on the corrected throttle valve angle. The corrected throttle valve angle is based on the offset and the sensed throttle valve angle.
In a further embodiment, the invention provides a fuel injection system in an engine. The system includes a first sensor that measures an engine parameter and provides a first output corresponding to a sensed value of the engine parameter. The system also includes a control unit coupled to the first sensor. The control-unit is operable to receive the output generated by the first sensor, operable to compute an expected value of the engine parameter, operable to determine an offset between the expected value of the engine parameter and the sensed value of the engine parameter, operable to determine a corrected value of the engine parameter, and operable to compute fueling calculations based on the corrected value. The corrected value of the engine parameter is based on the offset and the sensed value of the engine parameter.
Other features and advantages of the invention will become apparent by consideration of the detailed description and accompanying drawings.